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Extracellular inulinase producing bacterium was isolated from the rhizosphere soil of Agave sisalana and
identified as Bacillus sp. B51f by morphological, cultural, biochemical tests and 16S rRNA gene sequence
analysis. The maximum inulinase yield was 160.24 U/ml when 2% inoculum (0.8 OD545 nm) of the above
isolate was grown in M9 medium containing 1.5% inulin, 0.7% peptone, 0.3% Na2HPO4, 0.4% K2HPO4,
0.3% NH4Cl and 0.4% NaCl at pH 7, temperature 30°C for 24 hours at static conditions. The highest
inulinase activity was observed (173.41 U/ml) at pH 8 and 55°C which indicates it to be thermostable and
alkaliphilic. The effect of various metal ions and thermal stabilizers were checked on inulinase activity.
Ca2+ ions increased the enzyme activity whereas glycerol exhibited a stabilizing effect on the enzyme.
HPTLC analysis of hydrolytic prodcuts of inulinase revealed that inulinase hydrolysed inulin exclusively
into fructose which confirmed exo inulinase nature of the enzyme.
Keywords: Bacillus sp. B51f; Inulinase;Agave sisalana.